New Drug for Heart Attacks OKd for Use : Genetically Made TPA Expected to Save Thousands

The Food and Drug Administration announced approval today of a new genetically engineered clot-dissolving drug that could save the lives of thousands of heart attack patients a year.

FDA Commissioner Frank E. Young termed approval of the drug--widely known as TPA--”a major advance in the management of coronary heart disease.”

Officials of Genentech Inc., the California company that developed the drug, said that initial distribution will be to hospitals and that it should be available nationwide within two or three weeks.

While not the first drug developed through biotechnology, TPA is regarded as the first destined to have a dramatic and widespread impact and is expected to prove a financial bonanza for Genentech.

Expensive Dose

Company officials said the cost for U.S. doses has not been determined but added that it likely will be in the $2,000-per-dose range established in other countries.

The drug is an emergency treatment most effective when administered within the first minutes, preferably, after a patient has suffered a heart attack. The official labeling will call for its use “as soon as possible after the onset of symptoms.”

Young said 250,000 of the 800,000 people who suffer a first heart attack in the United States each year die within the first month.

“Early treatment (with TPA) may help reduce these deaths, but it may be even more important to many of us that early treatment can improve the quality of the years remaining,” Young said.

Natural Substance

TPA, or tissue plasminogen activator, is a substance occurring naturally in the human body, but not in the concentrated volume that will be administered to heart attack victims. It works by binding itself to blood clots and activating an enzyme in the clots that dissolves them.

Young said it “essentially eats away” the clot.

The dramatic potential of the drug stems from the fact that by dissolving clots in arteries leading to the heart, it shortens the time that blood flow to the organ is reduced and thus lessens the amount of muscle damage.

TPA will be marketed in the United States under the brand name Activase. It has been tested on 4,000 heart attack victims in clinical trials since early 1984.

In Cincinnati, test trials showed 91% of all blocked arteries were successfully unclogged after patients took the drug.

Dr. Charles Abbottsmith, director of cardiology at Christ Hospital in Cincinnati, has referred to TPA as the “penicillin of heart attacks.”